1. Field of the Invention
This invention relates to breakerless ignition systems for internal combustion engines and to distributors therefor.
2. Prior Art
The ignition system for an internal combustion engine generates timing pulses which indicate the instant during the piston stroke that the spark plugs should be fired and distributes these pulses to the individual spark plugs to cause them to fire in a preset order. In the conventional ignition system, mechanical breakers are used to generate the timing pulses and a rotating mechanical distributor directs the pulses to the appropriate spark plugs in sequence. Since the high voltage required to fire the spark plugs greatly limited the life of the mechanical breakers, ignition systems were developed in which the switching of the high voltage necessary to fire the individual spark plugs was accomplished by breakerless electronic switches such as silicon controlled rectifiers (SCRs). This significantly improved the life of the mechanical breakers which were still used for timing pulse generation. Subsequent developments have replaced the mechanical breakers for generating timing signals with magnetic and optical pulse generators. Many of the optical timing pulse generators, however, operate with a continuous light source which requires substantial electric power and therefore limits their use with magneto equipped internal combustion engines.
Further developments have resulted in a substitute for the conventional rotating mechanical distributor in the form of a transformer distributor. In such a system, the timing pulses are applied to a rotor which induces trigger pulses in angularly distributed secondary coils to fire the appropriate SCR controlled spark generating circuit. While the transformer distributor requires little power and has a long life, it is not suitable for use in a system with small firing angles because pulses can be induced under these conditions in two adjacent secondary coils simultaneously. This possibility of double firing also limits the amount of timing pulse advance that can be utilized with a transformer distributor.
A light activated system for applying energizing pulses to the injectors of an electronic fuel injection system is disclosed in commonly owned U.S. Pat. No. 3,895,612. In this system a single, continuously illuminated radiant energy source is used to sequentially activate the fuel injectors through a fiber optic which directs the radiant energy radially outward from the center of a disc rotated in synchronism with the engine to sequentially turn on circularly arranged photodetectors associated with the fuel injector activation circuits. No means are provided for advancing or retarding the pulses thus generated.
It is a primary object of this invention to provide a novel and improved internal combustion engine breakerless ignition system with a simple, inexpensive but reliable distribution means.
It is also an object of the invention to provide such a system which can operate at small firing angles.
It is another object of the invention to provide such a system which can accept full advance of the timing signal.
It is a further object of the invention to provide such a system which requires a minimum amount of power to operate.